Unless otherwise noted, all content was authored by Chip Taylor, edited by Jim Lovett and Sarah Schmidt, and published by Jim Lovett.

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1) Status of the Population

These updates are full of subjective opinions and this one is no exception. Last year on the trip to Mexico in mid March, I had the opportunity to watch the monarchs that were streaming north from the overwintering sites. I was disappointed by the weak flight and what appeared to be the poor condition of the butterflies. I couldn’t imagine how this torn and tattered population could reach the states and reproduce and increase the population from the all time low of 2.19 hectares measured for the winter of 2004-2005 - but they did. I underestimated the capacity of the monarchs to survive and reproduce once again.

The population wintered well this year. There were no ice storms or extremely low temperatures, nor was it too dry. And, on the trip to Mexico this March, as I watched the monarchs stream northward or up and down the mountains near the colonies, I was impressed by the robustness of their flight and their overall appearance. The proportion of the population that could be described as tattered and worn was low.

Moving North

Some monarchs begin leaving the overwintering sites in the last week of February. As I’ve mentioned before, there is no data or even extensive observational history of the remigration process. We need one. At the moment, we only have fragmentary reports of the return migration as it proceeds through Mexico. This year we learned from Shelley Whittall, who resides in Santiago de Queretaro (in the state of Queretaro) that she first noticed monarchs passing through the city on the 2nd of March. Queretaro is located 65 miles (108 km) to the north of Angangueo. If the advancing monarchs moved at an average rate of 25 miles per day, the expected pace for returning migrants, Shelley’s observation suggests that monarchs began leaving the overwintering sites around the 27th of February.

Conditions for Monarchs Reaching Texas

The monarchs arriving from Mexico move through Texas, so it is appropriate to focus on the conditions the monarchs encounter as they reproduce in this state and/or continue to move through the state to the east and north.

The title of one of the so-called Spaghetti westerns starring Clint Eastwood - “The Good, the Bad, and the Ugly” could be used to describe the weather greeting monarchs as they moved into Texas in early March. However, it would be more appropriate to change the order of the weather events to “the bad, the good and the ugly”. The bad refers to the abnormally high temperatures at the beginning of the month, the good to the rains in the middle of the month that gave some relief from the drought, and the ugly to the freezing temperatures that followed the rains and may have killed some larvae.

The following three figures show temperatures for March from three representative locations.

The high temperatures (red line) from 1-13 March are shown on the figures below for Texarkana, Arkansas (on the Texas/Arkansas border east of Dallas), for San Antonio, Texas and for Laredo, Texas. As you can see, the temperatures exceeded the normal highs (upper blue line) for each of these locations for most of this period. A cold front, bringing much needed rainfall, swept through Texas on the 14th.. Subsequent to the front, temperatures were closer to the normal range for most of Texas, however some areas experienced freezing temperatures after the 23rd. Additional rainfall swept through much of central on the 28th.

Until there is evidence to the contrary, I’m going to assume that hot, dry weather is deleterious to monarchs. Under hot conditions, i.e. temperatures in excess of 85 degrees F, monarchs begin to decrease their activities and, if the sun is unobstructed by clouds and the temperatures reach the 90s, many individuals will seek shade. In general, high temperatures increase metabolic rate, probably increase the demand for nectar and water, and decrease general activity, including reproduction. Such high temperature conditions, relative to temperatures in the mid 60s to low 80s, could increase mortality and decrease realized fecundity. Thus, it would appear that conditions were unfavourable for monarchs during the first two weeks of March, particularly in South Texas.

The Good: Rainfall

Drought conditions have developed in Texas over the last several months. In fact, as of the first two weeks of March, the drought has been the worst in Texas since the spring of 1996. The rainfall has begun to modify the drought conditions somewhat, but more rain will be needed throughout the state to bring soil moisture and plant growth back to normal. Maps showing the extent of the drought for the 14th and 28th of March are given below. A comparison of these maps shows that the area of extreme drought (in red) diminished due to the rains of the third week of March.

Drought should be bad for monarchs, right? I had always assumed this to be the case until I began analyzing the growth of the monarch populations relative to temperature and drought. If one considers drought, independent of temperature effects, we get mixed messages about the importance of drought. In the spring of 1996 there was a severe drought in Texas as the monarchs moved north through the state in March. Yet, the monarch population increased substantially from the winter of 1994-1995 to the following winter. In fact, the population the next winter (21.6 hectares) was the highest recorded since the colonies have been measured. In contrast, the population crashed to 2.83 hectares, the second lowest overwintering population yet recorded, after the spring drought of 2000. The drought maps for March of 1996 and 2000 are shown below. Clearly, factors other than drought determine the overall size of the monarch population the following winter. But, how could monarchs benefit, or not be harmed significantly, by some droughts and negatively impacted by others? Of course, not all droughts are the same. First, most droughts are going to have a negative impact on fire ants and most other predatory and parasitic insects. In the case of severe droughts, fire ant populations decline substantially. This effect is potentially significant and beneficial since, in much of Texas, fire ants are major predators of soft-bodied insects, including monarch caterpillars. Because milkweeds are deeply rooted perennials, if there is enough subsoil moisture, the plants will send up shoots. Thus, milkweeds can be available for oviposition by female monarchs even though soil moisture is too low to permit the germination of seeds or the growth of annuals. If conditions permit milkweeds to be available while limiting predators and parasites, monarchs could benefit from such moderately dry conditions. Other the other hand, severe droughts, in which the subsoil moisture is too low to permit growth of milkweeds, certainly would limit the growth of monarch populations by eliminating this essential resource from the habitats. Droughts could also have a negative impact by restricting the development and bloom of nectar sources needed to sustain adult monarchs.

The Ugly: Freezing Conditions

Freezing temperatures in the spring could strongly impact the monarch population by killing many of the developing larvae and freezing the emerging milkweeds. Such conditions prevailed in the spring of 1997 and may account for the drop in the overwintering monarch population from 21.6 hectares in 1996-97 to just under 6 hectares in 1997-98. While it is possible that the low temperatures from the 23rd to the 26th killed larger larvae in some areas of Texas, the lows just barely reached freezing in most regions and then only for short intervals. Therefore, the Ugly may not have been ugly after all.

The conditions in Texas have certainly been mixed this month. The first two weeks were too hot and dry in my estimation and could have limited monarch reproduction and longevity. The temperatures and moisture conditions were more favourable for monarchs the following two weeks and plant growth should have been aided by the rainfall in many locations. Since relatively few monarchs move into Texas before the end of the first week of March, unless high temperatures in Mexico severely limited the number of monarchs reaching Texas, the monarchs should be off to a relatively good start. We will be able to assess the size and success of the returning population in the coming months by tracking sightings of overwintered migrants as they continue to move north through April and by assessing the number of new adults that move north from Texas in May and early June.

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2) Tag Recoveries

I’ve got a bad memory. When contemplating how much money I needed to buy tags this year, I estimated that only a few hundred tags remained to be recovered from the winter- kills of 2002 and 2004. So, when planning the trip for this year, I estimated that combining the recoveries from this winter with those from previous years I would only need $3000 to pay for the 600 or so tags that would be available. I was wrong. I should have reread the Update from last March in which I estimated that 500-600 tags remained in the hands of the guides and ejido members. That estimate was fairly accurate.

We arrived at El Rosario late on the afternoon of 7 March and soon departed with no pesos and over 600 tags. The $3000 was gone and there were still tags to buy. We managed to dip into our reserve/emergency funds to acquire more pesos and ended up with returning to Lawrence with 879 tags. Due to the generous contributions of several Monarch Watch supporters, additional tags were purchased, bringing the total tags acquired in Mexico in 2006 to well over 900. So, once again the tagging program has put us in a bind financially by exceeding our budget. However, the data is fantastic and with each year new insights seem to spring from the data.

If you would like to make a tax-deductible contribution to our Tag Recovery funds please visit

Sarah Schmidt has been assembling the data from the recovered tags, a much easier process now that all the records from the datasheets have been entered into a database. Most of the recoveries from Mexico will be posted during the first weekend in April and all of the recoveries will be posted by the end of April.

Don't forget - you can search print your own certificate(s) from the Recovery Database at

Please note: if you notice that we don't have the data associated with your tag (or we contact you asking for the data), please be sure to send in all of your tagging information for that year. While we do appreciate getting the tagging information for the tag that has been recovered, it's great to get all of the information in case another tag from that series is recovered at another time.

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3) Convergence of Monarch Experts and Filmmakers

Although I’ve run into Bill Calvert and his tour groups on many of my trips to Mexico - and I did this year as well - I’m more likely to encounter other monarch experts at meetings rather than in Mexico. So, it was quite extraordinary to meet up with a number of monarch experts, including some I hadn’t met before, on my recent trip to Mexico. After a long day travelling to Cerro Pelon and Herrada, Janis Lentz and I returned to the Hotel Don Bruno at 9 pm. There was a large group of guides at the entrance to the hotel and it turned out they were waiting for us. They had tags and they were hopeful we had the money to buy them. Fortunately, Carole Jordon was able to change some money for us that morning in Zitacuaro. We quickly organized another tag buying event and managed to buy more than two hundred tags before we ran out of money again. We then made our way to the dinning room at the Don Bruno where we encountered a contingent of monarch experts including: Lincoln Brower (Sweetbriar College, VA), Karen Oberhauser (Univ of Minnesota), Michael Boppré (Forstzoologisches Institut der Universitat Freiburg)*, Dick Vane-Wright (British Museum of Natural History)** and Don Davis (Toronto). They were enjoying after dinner libations and desserts together with film-makers Phil Streather and Jonathan Barker, who were researching the basis for an IMAX film tentatively titled “Flight of the Butterflies”, photojournalist Mr. Medford Taylor (National Geographic), forester Jose Luis Alvarez of the La Cruz Habitat Protection Project, environmentalists Rebecca Goodwin, Gretchen and Umburto Bauta. Kay Milam, a filmmaker who is working on a project called “The Butterfly Trees”, stopped by for a brief chat as well. We had the extraordinary good fortune to have breakfast with these folks the next morning as well. The only downside to this meeting was that it was too short. We could have talked for hours, if not days.

When monarch folks get together, the talk tends to focus on monarch lore and what we know and don’t know about these butterflies. One of the topics that arose during this discussion was the geographic composition of the monarch colonies. The stable isotope study in 1996 (Wassenaar and Hobson 1998) had shown that the monarchs from colonies on different mountainsides were completely mixed geographically such that there were no colonies that contained butterflies from a specific area of the United States. In geographic terms, the butterflies were randomly distributed among all the colonies.

Using the tagging data from the massive number of recoveries obtained after the winter storm of January 2002, we asked a similar question. The analysis was presented on pages 16-17 of the 2001 Season Summary. Again, the data indicated that the monarchs originating from different parts of the country were randomly distributed among the monarch colonies. Most impressive was the result for the tagging conducted at the Baker Wetlands, Lawrence, KS on the 15th of September 2001. These data showed that the recoveries from this location were distributed in the same proportions across the three main recovery sites, El Rosario, Sierra Chincua, and Cerro Pelon, as were the recoveries themselves. For example, if 78% of the total recoveries were obtained from El Rosario, then approximately the same percentage of the total recoveries of tags from the wetlands were obtained from this location.

At the time of the analysis, we had obtained 80 tags applied at the wetlands on the 15th of September 2001. Because we have continued to acquire tags from the 2002 winter-kill, we’ve now recovered a total of 160 tags that were tagged on this day. Further, the extraordinary tagging success of Tom Murphy from Cannon Falls, MN, allows us to ask the same question with another set of data. Tom tags his monarchs as they visit the patches of Liatris planted behind his house. A query of our tag recovery database through March 2005 shows that 173 tags were recovered from butterflies Tom tagged between 11-19 August and 28 August - 5 September. A total of 3376 monarch tags were recovered in Mexico from butterflies tagged in 2001 through March 2005. As you can see in Table 1 the distributions of the butterflies tagged by Tom Murphy and those from the Baker Wetlands among the three colonies are similar to those of the entire sample. A chi-square test shows that neither distribution differs significantly (p>.01) from expected. Once again, these data affirm that the butterflies reaching Mexico from given areas of the United States are randomly distributed among the monarch colonies in Mexico. These numbers will change slightly when the tags purchased in 2006 are added to the database.

Table 1. Distribution among monarch colonies in Mexico of butterflies tagged in 2001.

All TagLocations

Wetlands

Tom Murphy

Observed

Expected

Observed

Expected

El Rosario

2620

133

125

124

135

Sierra Chincua

551

22

28

34

30

Cerro Pelon

203

5

7

15

8

Total

3376

160

160

173

173

Chi-Square

-

p < .30

p < .02

*Michael Boppré is known for his work on insect pheromones, especially his numerous studies of the pheromones unique to male Danaine butterflies.

**Dick Vane-Wright is the co-author with P. R. Ackery of the outstanding compendium on the Danainae, the sub family of Nymphalid butterflies to which the monarch belongs - Milkweed butterflies: Their cladistics and biology. 1984.

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4) Monarch Waystation #500

Congratulations go out to Tom Murphy of Cannon Falls, MN who recently applied for certification of his milkweed/monarch habitat and is now the proud caretaker of Monarch Waystation #500. Below is a picture of one of Tom’s patches of Liatris (blazing star).

When in full flower, these plants attract an exceptional number of monarchs, allowing Tom to tag 2000 or more monarchs per year. With nearly 300 recoveries, Tom currently holds the all-time record. I’ll write up more about this amazing record in another update.

So who will register Monarch Waystation #1,000? Hopefully we will find out soon! To see a complete listing of Monarch Waystations to date, visit

We are a long way from our goal of 10,000 Monarch Waystations in the first three years of the program (started almost one year ago) but we hope to pick up steam this year and see a dramatic increase in the number of milkweed/monarch habitats created all over North America, and around the world. We have certified sites in 37 U.S. states, 2 provinces in Canada, the Virgin Islands, and the Bahamas and we are excited to hear from monarch enthusiasts all over the globe (lots of interest in New Zealand!) that plan to create and certify Monarch Waystations this year. Could you be the first in your area? Check out the Monarch Waystation Registry and then get your habitat certified! :-)

Monarch Waystation Seed Kits

As we mentioned last month we now have a limited number of seed kits available in two versions: a standard kit and a California kit. Once our current inventory runs out, additional kits will not be available until next year so if you would like seeds this year please be sure to order early (Monarch Watch Shop item#125522):

Each month at Monarch Watch brings something new. This month was eventful for a number of reasons, among which was the arrival of an email from Cristina Loayza, a teacher at the Leonardo Da Vinci school (www.ldavinci.edu.pe) in Lima, Peru. In her email, Cristina described a monarch breeding program being used in the school to introduce students to science. This program is a “wow!” for two reasons: it is the only school program that I know of that uses monarchs to educate students outside of North America and, by being in Lima, Peru, the location is close to the known southern limit of monarchs in western South America.

It has been three years since we began a very small butterfly breeding program here in Lima, PERU, South America. We too have Monarchs. They don't migrate to Mexico but they do move around to warmer places during the winter in Lima. Our Capital City is not that cold but cold enough for them to fly off to warmer resorts, like Chosica, Chaclacayo, Cieneguilla and others that are close to us.

We are a progressive education school and the program is currently geared to children from Nursery until second grade in the lower school, 3 to 8 years old, and the monarchs are the basis of the science program for them. This February we released over 200 monarch butterflies but our main problem is that we do not have enough milkweed plants. The Asclepias sp they feed and breed on here in Lima, the tropical milkweed, curassavica, and butterfly weed, tuberosa, are not common and are only found around river beds. Getting to these locations is quite difficult here and nobody sells seeds or plants. So, we began our own milkweed farming. Unfortunately, the butterflies came when we did not have enough milkweeds and as you can imagine, the caterpillars ate them all.

We were able to save over 300 caterpillars from death by inviting the Agrarian University to join in our efforts but they too do not have enough milkweed. We are doing our best to acquire enough seeds and we have decided to cover the milkweed areas with Rachelle mesh to allow the plants to grow enough for the butterflies and caterpillars to feed on. We hope the butterflies will not give up on us.

Because we have created a place for butterflies, we find that other butterflies are coming around to the school also, some big beautiful dark yellow ones and some medium sized ones with blue/violet hues. We don’t know their names yet.

We will try to send you more photos of our little project but I thought you would like to know that in some other part of the world someone is trying to educate children about butterflies and to have them work in an active program.

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6) Spring Open House & Plant Fundraiser

You are cordially invited to join us on Saturday, May 13th 8am-3pm for an Open House and Plant Fundraiser at our facilities on West Campus at the University of Kansas in Lawrence. We are located in Foley Hall (2021 Constant Avenue) near the greenhouse. Nearly 4,000 butterfly plants (both annuals and perennials) including seedlings of seven milkweed varieties, will be available (modest contributions are suggested). We will provide refreshments, lots of show & tell, videos and games for children, iChat videoconferencing demonstrations, and, of course, monarch butterflies!

We hope to see you there, but if you can't make it to Lawrence we'll have "live" photos and maybe a webcam or two for you to check out online during the day - for more information and a map visit

We are in the middle of a big revision of our online storefront, loading it up with items we think you'll like (in addition to all of our "traditional items" - tagging kits, rearing kits, etc.), and making it easier to find the items you want. If you have any comments or suggestions for improvement please feel free to drop us a line at monarch@ku.edu anytime - we'd love to hear from you.

Remember, every purchase from the Monarch Watch Shop supports our educational, conservation and research programs so be sure to keep us in mind when you're doing a little shopping:

Monarch Watch is losing one of its two Program Assistants this summer so we are now in the process of searching for a replacement to take over this full-time position. If you're interested in applying, or know someone that might be, please see the complete job posting available at

All applications must be submitted online. Application deadline/initial review date is April 17, 2006.

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9) About Monarch Watch

Monarch Watch is a not-for-profit educational outreach program based at the University of Kansas. We manage several educational, conservation and research programs - focusing on the monarch butterfly, its habitat and the spectacular fall monarch migration.